There are many instances where it is desirable to maintain a consistent painted surface quality. This may be the case for an object assembled from several painted parts or for a manufactured object having a large painted surface. In particular it may be desirable to control gloss (shininess), distinctness of reflected image (sharpness) and orange peel (roughness) of the painted surface. Control of these surface qualities requires measurement. It would also be desirable to automate these measurements. In a typical manufacturing operation painted parts move on an assembly line. Thus it would also be desirable to make these surface quality measurements on moving objects.
Prior instruments for making surface quality measurements have problems. A first type of prior instrument required a subjective determination by a trained observer. This type of instrument does not provide a repeatable measure when used by different operators. Automatic optical instruments exist in the prior art for making such surface quality measurements. Some of these instruments make measurements of very small areas of the surface. Other such instruments include rotating mirrors. Such devices are often unsuitable for the typical manufacturing environment where dust may enter delicate mechanisms. Thus it would be desirable to provide an automated surface quality measurement apparatus which measures an extended surface area and does not employ moving parts.